Luminous tube



Filed Dec. 14. 1928 INVENTOR ATTORNEY interior electrodes.

crm s. Cannara,

or Lone IsL ..y

Younger. r., Assiettes P.ro .e romiacoaroaarron or Nawroax Applicationmed Detemher 14, 19%8. erial o. Sl.

m quartz tube and none of itleak between the 'eiicients of expansionofglass and quartz.l

external glass tube andinternal quartz tube.

The making of a sutlcien-tly tight seal to prevent leakage has' alwaysbeen a diflicult matter because of the widely different 'oo- Because ofthis difference it has beenpractt. 'cally impossibleto make'anVeffective seal between an external glass tube and an internal quartztube.

My invention solvesthis diiiiculty and pro. vides a seal between aluminous glass tube and' an internal quartz tube which will effectivelyprevent electrical leakage and will maintain an electrically tight jointbetween the two,

irrespective of their different rates of expanwith a quartz tube'sealunderstood attention is directed to the accompanying drawing showin aluminous tube therein by means which comprises my invention. r

Fig. 1 is a longitudinal cross-section of a tube embodying my inventionand Fig. 2 is a transverse section of the tube of Fig. 1 at line 2 2.

The luminous tube proper equipped with the usual internal electrodes visshown at 1. A quartz tube 2, through which th'e entire luminousdischarge is to pass, is sealed withl in it. The external diameter ofthequartz tube is somewhat smaller than the internal diameter of thatportion of theglass tube into which it is to be sealed. Sealing iseffected by means of twoA or more annular rings 3, 4

and 5 made of metallic gauze, such as copper or iron. These rings areplaced around the quartz tube as shown and are of such internal andexternal dimensions' that they lit snugly the 4outside of the quartztube and the inside of the glass tube, thus holding the quartz tube Inorder that the invention may be readily mrow LIGHT, me.,

in Position inl spaefreiaaon a the glass? tube.l The resilient nature ofthese rings permits'themto lcompress or expand as the case may be, sothat they will always mail4 tain contact with the two tubes, as abovedescribed, irrespective of the variations in the diameter of the tubescaused by changes' in tem erature.v l y O viou'sly such aseal is a poorone m chanically, but electrically it 1s perfect for the followingreasons. of rings, asfor example, rings 3 ande and .4 and 5 togetherwith the annular spaces between them comprise rsmall discharge tubes,the .rings lormingv the electrodes thereof'.v Thus the two rings 3 and 4are the electrodes for a small tube consisting of these two rings andthe space between them. Similarly the' rings 4 and 5 form'the electrodesof a similar small discharge tube. I, Y. c All of these small tubes arein series. It

is characteristic of luminous tubes of the 'class described that inoperation a lare e drop in potential occurs at the catho which issubstantially independent of the distance between the cathode andtheanode. Thisl being so the cathode drop in potential of each of the smalltubes, .constructed as labove described, will be found to besubstqntially the same as that of the luminousA tu e.

Since these small tubes are in series their total drop in potentialwill. be lthe sum of their individual drops in potential and the totaldrop in potential of the series of vsmall tubeswillbe Agreater than thedrop'il'i' potentialbetween'the main electrodes of the luminous tubeproper. Consequently, a.

highly effective seal against electrical leak' 4 age between the glassand the quartz tube is eiected by my invention, by means which Ibelieveto be distinctly novel.

It is important that the actual spacel between the metal rings and thewalls ofthe The succeedingpair ce f Yan

I claim as new therein and desire to secure by Letters Patent is asfollows z v 1. A luminous tube, comprising a glass envelope, a cathodeand an anode therein, a quartz tube within said glass envelope, saidquartz'ltube spaced from said glass envelope by resilient electricallyconductive 'uctive rings spaced `a said rings being spaced apart fromeacotherf..V v

2. Means for securing a uartz tube within a luminous tu of lass,comrising a multiplicity of electrically conrt from one another andmaintaining t e quartz and glass tubes in spaced relation.

3. A luminous discharge tube, comprisxg an external t envelo a cath eand an anode therein, a tube o different insulating material than the Yexternal envelope therein, said tube being envelope by means to preventthe y s: 1 of electrical discharge between sai envelope and said tube. n

velope and tubular member forming a plurality of short discharge tubesin series.

8. A luminous electrical discharge tube comprising an external envelopecontaining 'a rarefied gas, electrodes at opposite ends of saidenvelope, a tubular member within the envelope and vof less diameterthan the envelope, electro-conductive means between the envelope, andthe tubular member, the distance between said means and the wall of theenvelope and between said means and the wall of the tubular member beingof the order of the mean free path of the atoms of said-gas. l

RAYMOND R. MACHLE'I"I.

spaced 'from sald V'4. A luminous discharge tube, comprising an externaltransparent envelope, a cathode and an anode therein, a tube therein ofdifferent material than the external envelo e, said tube being spacedfrom said envelope y means to pievent the p of electrical dischargetween said envelope and said tube, said means co-operating with said'cathode and anode to maintain, while the tube is in operatiomaresistance to the pass-ge of electrx' 'cal current between theexterenvelope and the internal quartz tube figer the resistance throughthe quartz 5. 'A luihinous electrical discharge tube,

comprising an external envelope, a cathode and an anode therein, aquartz tube so posi- 'tioned that the/electrical discharge between heuartz tube at intervals along the 'lengths o the quartz tube thusforming in 5'5 effect two or more small discharge tubes in,

series, the resistance of which to the starting and passage ofelectrical current is greater lll than the resistance between the maincathode and anode of luminous tube than the' quartz tube.

7. A luminous electrical discharge tube comprising an envelope,electrodes at op osite ends of said envelope, a tubular member withinthe 'envelope and of less diameter than the envelope, and means betweenthe en-

